Method for multi-network data transmission

ABSTRACT

The invention concerns a data transmission method for connecting at least a mobile transceiver (MOB) to a communication network (NW) selected among a plurality of such networks (NWi), i=1 to 5. The inventive method is characterized in that it comprises a step of locating and identifying a transceiver (MOB) adapted by its geographical location to communicate with at least two different communication networks (NW 1  and NW 2 ), and a step of transmitting to said transceiver (MOB) characteristics particular to the networks which are operational in the site where the transceiver (MOB) has been located. The invention enables to select only the transceivers which are located in zone where several communication networks are operational, so as to send and information to them selectively, thereby not disturbing the other transceivers present in said region.

This invention concerns a method for transmitting data intended to beplaced in communication with a communication network selected from amultiplicity of such networks, with at least one mobiletransmitter/receiver, said communication networks each having specificcharacteristics that differ from one network to another.

These types of methods are, for example, commonly used to allow bi-modalradiotelephones to communicate with, as desired, a first GSM network ora second DCS1800 network. In this example, the technologies of the firstand second networks are both cellular and sufficiently similar so thatswitching from one network to another requires only minor adjustments ofthe transmitter/receiver, such as reprogramming the oscillatingfrequency ranges in transmission and receiving tuners.

The transmitter/receiver can, however, be placed in multi-networkenvironments where the networks present have characteristics that differgreatly from one network to another, as is the case for UMTS cellularnetworks, IRIDIUM or GLOBALSTAR satellite networks or local DECT or WLANnetworks.

In certain cases, it may be advantageous for a mobiletransmitter/receiver located in a multi-network environment to switchfrom one network to another, for example in case of the saturation ofthe network with which it is connected, or if another network allows itto realize savings in terms of transmission costs or battery life.

The invention is tied to the following considerations:

The same cell of a first cellular network may, for example, include oneor more areas in which one or more associated local networks distinctfrom the first network are operational. A mobile transmitter/receiver,configured to communicate with the first network, that enters this typeof area and is endowed with suitable equipment could switch to the localnetwork in order to use more advantageous capacities. The mobiletransmitter/receiver concerned must, however, have been alerted inadvance of the very existence of this type of possibility.

Information concerning the various areas included in the cell in whichother communication networks are operational could be sent continuouslyto all the mobile transmitter/receivers dependent on said cell, but thismeasure would cause a significant increase in the communication volumewithin the cell, which could result in the saturation of said cell ifthe number of transmitters/receivers present in this cell is large.

This invention aims to eliminate this disadvantage to a large extent byproposing a data transmission method thanks to which atransmitter/receiver located in an area in which several communicationnetworks are operational can be alerted of this without such a measurecausing a significant increase in the communication volume for thenetwork with which said transmitter/receiver is in communication.

Indeed, according to the invention, a data transmission method conformto the introductory paragraph includes:

-   a localization and identification step for a transmitter/receiver    rendered capable by its geographic situation of communicating with    at least two different communication networks, and-   a transmission step, to a transmitter/receiver identified at the end    of the location and identification step, of characteristics specific    to operational communication networks in the location where said    transmitter/receiver was located.

The method according to the invention makes it possible to select, fromall the transmitters/receivers included in a same cell, to repeat theprevious example, only the transmitters/receivers located in areas whereother networks with which they are capable of communicating areoperational. An informational message may then be sent selectively tothe transmitters/receivers thus selected, which will not perturb theother transmitters/receivers present in the cell.

This advantage takes on an even larger dimension in an application ofthe method according to the invention to a set of cells of acommunication network, a set within which are disseminated areas inwhich at least one other communication network is operational.

Thanks to the step involving the transmission of the characteristicsspecific to the communication networks operational in the location whereit was located, the transmitter/receiver identified can be informed, inreal time and as it moves, of the various possibilities offered to itinside the area in which it is located.

According to a variant of the invention, the method described above mayinclude a step in which the configuration of the transmitter/receiveridentified at the end of the location and identification step isanalyzed and a step during which a possible compatibility of saidconfiguration with the characteristics specific to communicationnetworks operational in the location where said transmitter/receiver waslocated is evaluated.

The transmitter/receiver identified can then evaluate its ability to usethe alternative network or networks thus described to it.

Indeed, if said communication networks are very different from oneanother, the transmitter/receiver may not be able to adapt itselfimmediately to the characteristics specific to an alternative network.For example, the deployment of a specific antenna may be necessary forcompatibility with said network, or it may be necessary to load ahardware or software module or even for the user of thetransmitter/receiver to indicate his acceptance of a new rate grid.

According to another variant of the invention, which mightadvantageously be used cumulatively with the variant previouslydescribed, a transmission method as described above may include a stepduring which the configuration of the transmitter/receiver identified atthe end of the location and identification step is adapted, whichadaptation step is intended to adapt said transmitter/receiver to atleast one communication network operational in the location where saidtransmitter/receiver was located and distinct from a network with whichthe transmitter/receiver is already compatible.

This step can be implemented selectively, for example at the end of theevaluation step cited earlier, or routinely, without taking into accountthe prior configuration of the transmitter/receiver identified as beingsuitable for communicating with the new network.

The location and identification step can be implemented in differentways. The mobile transmitter/receiver, may, for example, be the subjectof radiodetection by triangulation on the part of base stations of atleast one terrestrial communication network or satellite network. Thisradiodetection will produce coordinates for the transmitter/receiverthat will be compared with the pre-set contours of the areas in whichthe different communication networks are operational. If the coordinatesof a mobile transmitter/receiver are included in a surface area definedby such a contour, said transmitter/receiver will be identified assuitable for communicating with the corresponding network.

In one of its applications, the invention also concerns atelecommunication system including at least one mobiletransmitter/receiver intended to be placed in communication with acommunication network selected from a multiplicity of such networks,said communication networks each having specific characteristics thatdiffer from one network to another, a system characterized in that itincludes:

-   -   means for locating and identifying a transmitter/receiver        rendered capable by its geographic situation of communicating        with at least two different communication networks, and    -   transmission means intended to transmit to a        transmitter/receiver identified by the location and        identification means characteristics specific to communication        networks operational in the location where said        transmitter/receiver was located.

In a variant of this application of the invention, the system describedabove may include means for analyzing the configuration of thetransmitter/receiver identified at the end of the location andidentification step, and a step for evaluating a possible compatibilityof said configuration with the characteristics specific to communicationnetworks operational in the location where said transmitter/receiver waslocated.

In another variant of the application of the invention described above,the telecommunication system will also be equipped with means foradapting the configuration of the transmitter/receiver identified at theend of the location and identification step, which adaptation means areintended to make transmitter/receiver compatible with at least oneoperational network in the location where said transmitter/receiver waslocated and distinct from a network with which the transmitter/receiveris already compatible.

The means of location and identification may also include base stationsbelonging to one or more terrestrial telecommunication networks or evensatellites, for triangulating a position of the transmitter/receiver.

The invention also concerns a radiotelephone capable of performing thefunctions of a mobile transmitter/receiver used in a data transmissionprocess or a telecommunication system as described earlier.

The features of the invention mentioned above, along with as others,will become clearer upon reading the following description of an exampleof embodiment, said description being given in relation to the appendeddrawings in which:

FIG. 1 is a diagram describing a telecommunication system according to amode of implementation of the invention,

FIG. 2 is a diagram describing a variant of this telecommunicationsystem,

FIG. 3 is a flow chart describing a data transmission method used insuch systems, and

FIG. 4 is a functional diagram describing a possible mode of embodimentof a radiotelephone capable of being used in systems or methodsrepresented previously.

FIG. 1 is a schematic representation of a telecommunication system inwhich the invention is implemented. In this example, the system includesa first cellular communication network NW1 that presents a first, asecond and a third cell C1, C2 and C3, each equipped with a base stationBS1, BS2 and BS3. A second communication network NW2 is operational in aperimeter associated with the first cell C1, a third and a fourthcommunication network NW3 and NW4 being operational in a perimeterassociated with the second cell C2 and a fifth communication network NW5being operational in a perimeter associated with the third cell C3. Inthe scenario described here, the second, third, fourth and fifthcommunication networks are local networks, for example DECT or WLANnetworks. In other scenarios, any of these networks can be of a regionalor even global dimension and cover one, more or all the territoriescovered by the cells of the first communication network NW1.

The telecommunication system described here also includes a mobiletransmitter/receiver MOB, represented in the form of a radiotelephone,but which can also be a personal organizer or any portable item,provided that it is equipped with transmission and receivingfunctionalities. During one of its travel movements, represented in thefigure by a directional arrow, said mobile MOB enters an area in which,in addition to the first communication network NW1, the secondcommunication network NW2 is operational. This event is detected by acommunication network management infrastructure. Indeed, the position ofthe mobile transmitter/receiver MOB is determined continuously by saidinfrastructure by means of triangulation performed by the base stationsBS1, BS2 and BS3 of cells C1, C2 and C3. Each of the stations identifiesa direction according to which a signal received from the mobiletransmitter/receiver MOB has a maximum or minimum power. Theinfrastructure determines a point of convergence of the directions thusidentified and deduces from it the coordinates of the mobiletransmitter/receiver MOB. These coordinates are compared with thepre-set contours of the areas in which the different communicationnetworks NW2, NW3, NW4 and NW5 are operational. If the coordinates ofthe mobile transmitter/receiver MOB are included in a surface area A2defined by this type of contour, said transmitter/receiver MOB isidentified as capable of communicating with the corresponding networkNW2.

The infrastructure can then send an informational message selectively tothe transmitter/receiver thus identified, which will not perturb othertransmitters/receivers present in the cell C1.

In the example described previously, three base stations of the samecellular communication network are used to locate the mobiletransmitter/receiver MOB via radiodetection. In other modes ofimplementation of the invention we can use only two base stations oreven a single base station for this purpose if, in addition to adirection according to which a signal received from the mobiletransmitter/receiver MOB has a maximum power, it is capable ofidentifying a temporal attenuation of said signal based on a distanceseparating the mobile transmitter/receiver MOB from the base stationconsidered. It is also possible to use base stations belonging todifferent communication networks, as long as each of these stationscommunicates with a common management infrastructure capable ofcompiling the information coming from the different base stations.

We can also use measurements of the time necessary for a signaltransmitted by the mobile transmitter/receiver MOB to reach differentbase stations or even the time necessary for signals transmittedsynchronously by base stations to reach the mobile transmitter/receiverMOB, which will then communicate to the infrastructure the temporaldeviation values it has measured. We can also envision combining powerlevel and temporal measurements.

FIG. 2 is a schematic representation of a variant of a telecommunicationsystem as described above in which the location and identification stepis performed by means of satellites placed in orbit around the celestialbody, Earth, for example, on whose surface said mobiletransmitter/receiver MOB is intended to move. The elements of thistelecommunication system that are common to the one represented in thepreceding figure were assigned the same reference numbers and will notbe described again here.

In this example, the position of the mobile transmitter/receiver MOB isdetermined by the infrastructure by means of triangulation performed byfirst, second and third satellites S1, S2 and S3. These satellites maybelong to a communication network with which the mobiletransmitter/receiver MOB is in communication, in which case said networklocates the mobile transmitter/receiver MOB according to time and powermeasurement techniques mentioned earlier. The satellites S1, S2 and S3can also belong to another network or a specific location constellation,for example of the GPS type, in which case the mobiletransmitter/receiver MOB itself determines its position via temporalmeasurements and periodically reports its position to its managementinfrastructure. In all cases, the coordinates of the mobiletransmitter/receiver MOB are intended to be compared with thepre-determined contours of the areas in which the differentcommunication networks NW2, NW3, NW4 and NW5 are operational. Thetransmitter/receiver MOB will be identified as capable of communicatingwith the network NW2 if its coordinates are included in a surface areaA2 defined by the corresponding contour. The infrastructure may thensend an informational message selectively to the transmitter/receiverMOB thus identified, which will not perturb the othertransmitters/receivers dependent on the first communication network NW1.

FIG. 3 is a flow chart that illustrates the process of a method conformto the particular mode of implementation of the invention

In an initial step COM1 of this method, a mobile transmitter/receiver isconfigured to communicate with a first communication network.

In a next step LOCM, called location and identification, saidtransmitter/receiver is identified as being equally capable, as a resultof its geographic situation, of communicating with a secondcommunication network.

In a next informational step INFO, the transmitter/receiver identifiedat the end of the location and identification step receives, from amanagement infrastructure of the first communication network, forexample, a message describing characteristics specific to the secondcommunication network that is operational in the location in which thetransmitter/receiver was located.

In a next configuration analysis step ANALYS, the transmitter/receiveridentified analyzes its own configuration.

In a next test step EVAL, said transmitter/receiver determines whetherthis configuration is compatible with the characteristics specific tothe second communication network. If this is not the case, during a nextstep REP, the transmitter/receiver sends a report to the infrastructureto indicate to it that a switch to the second communication network isnot possible. In a next reconfiguration step CONFIG, thetransmitter/receiver considered then attempts to adapt its configurationto the specific characteristics of the second communication network, forexample by modifying the configuration of its radio parts or even byordering a user of said transmitter/receiver to deploy an antennanecessary for signal exchanges with said second network. This step isfollowed by another configuration analysis step ANALYS, then by anothertest step EVAL, at the end of which, if the configuration of thetransmitter/receiver considered is successfully adapted to the specificcharacteristics of the second communication network, thetransmitter/receiver signals the infrastructure that it is ready to endits link with the first communication network and to effectively enterinto communication with the second communication network during a stepSW2. In a variant of this step SW2, the transmitter/receiver may switchimmediately to the second communication network without sending anyprior warning to the infrastructure.

If, on the other hand, the new configuration of the transmitter/receiveris still not compatible with the specific characteristics of the secondnetwork, the transmitter/receiver still does not switch to the secondcommunication network and sends a new report to the infrastructure toinform it of this state of affairs during a new step REP.

In certain situations, a switch to the second communication network canbecome necessary in order to avoid losing the communication, forexample, because the first network is saturated. We can thereforearrange for the possibility of forcing the transmitter/receiver toswitch to the second communication network at the end of a preset numberP of configurations. To this end, the method according to the particularmode of implementation described here provides for the initialization atzero of a counter (N=0) during the information step INFO, said counterbeing incremented (N=N+1) before each reconfiguration step CONFIG.Before each configuration analysis step ANALYS, the content of thecounter is compared with the pre-set number P. In case of equality, thetransmitter/receiver is automatically placed in relation with the secondcommunication network during a step SW2. In other words, thetransmitter/receiver identified can refuse or delay a switch to thesecond communication work P times, but must obey request (P+1) or acommunication in progress will be interrupted for lack of compatibilityof the configuration of said transmitter/receiver with thecharacteristics specific to the second communication network.

In a particular mode of implementation of the invention, by selectingP=0 we can require the transmitter/receiver identified as being capableof communicating with the second communication network to switchimmediately to said second network without any concern for its priorconfiguration. However, this choice risks interrupting the communicationin progress if said prior configuration is not perfectly suited to thecharacteristics specific to the second communication network.

FIG. 4 is a schematic representation of a possible mode of embodiment ofa radiotelephone RT capable of fulfilling the functions of a mobiletransmitter/receiver in a data transmission method or a data processingsystem described above. This radiotelephone RT includes a principalcontroller CNT, typically constructed on the base of a microprocessorintended to handle the general management of the various functionalitiesof the radiotelephone RT, as well as to manage a man/machine interfacethanks to which a user can communicate with the radiotelephone RT, aninterface that comprises in this example a keyboard KB, a screen SCR, amicrophone MC and a speaker HP. The principal controller CNT must alsomanage high-level communication protocol layers that are stored in amemory ROM specific to it.

The radiotelephone RT also includes a DSP signal processor intended toprocess signals transmitted or received by the radiotelephone RT inbasic band. The radiotelephone RT also includes a radio part RF,adaptable by software means to different communication networks NW1, NW2and to different associated frequency bands through loading in a memoryRAMRF of the radio part RF of corresponding software modules Prog1,Prog2 that come from a memory MZ and contain information related to thecharacteristics specific to the other networks NW1, NW2. Theradiotelephone RT described here can receive two antennas ANT1 and ANT2each adapted to one of the networks NW1 or NW2, antennas whose use bythe user of the radiotelephone can be detected by presence sensors C1and C2 of the antennas ANT1 and ANT2.

The operation of the radiotelephone RT can be described as follows:

We presume that, during a first phase, the radiotelephone RT is incommunication with a first communication network NW1, a first antennaANT1 then being active. A first software module Prog1 is loaded into thememory RAMRF of the radio part RF, and into the memory RAMDSP of the DSPsignal processor. When the radiotelephone RT enters an area in which asecond communication network NW2 is operational in addition to the firstnetwork NW1, a message sent by a management infrastructure of saidnetworks via the first communication NW1 network alerts theradiotelephone RT of this state of affairs. This message will describecharacteristics specific to the second network NW2 and may contain asoftware module Prog2 to mitigate the possible absence of said module inthe memory area MZ of the radiotelephone RT. The software module Prog2thus received will be stored on the order of the principal controllerCNT in said memory area MZ.

After receiving this message, the radiotelephone RT evaluates whetherits configuration is compatible with the characteristics specific to thesecond communication network NW2. In particular, the principalcontroller CNT sounds the memory area MZ to verify the presence there ofthe software module Prog2 necessary to adapt the radio part RF to thesecond communication network NW2, and sounds its own memory ROM to lookfor the high-level protocol layers that correspond to said secondnetwork NW2 and observes the status of a presence sensor C2 of a secondantenna ANT2 necessary in this example for informational exchanges withthe second communication network NW2.

The radiotelephone RT then proceeds with making itself compatible withthe characteristics specific to the second communication network NW2, astep during which the principal controller CNT selects for itself theadequate high-level protocol layers and orders the loading of thesoftware module Prog2 into the memories RAMRF and RAMDSP of the radiopart RF and of DSP signal respectively. If the second antenna ANT2 isdeclared absent by the presence sensor C2, the adaptation step mayinclude a request to the user via the man/machine interface to ask saiduser to connect the second antenna ANT2. The adaptation step may alsoinclude the generation, by the principal controller CNT, of a request toa server, not shown in the figure and included in the firstcommunication network NW1, to download the second software module Prog2if this module is absent from the memory area MZ and was not included inthe message alerting the radiotelephone RT of the existence of a secondcommunication network NW2 operational in the location where theradiotelephone RT was located.

At the end of this adaptation step, the radiotelephone RT can beconnected to the second communication network NW2 under optimalconditions.

1) data transmission method intended to place a communication networkselected from a multiplicity of such networks into communication with atleast one mobile transmitter/receiver, said communication networks eachhaving specific characteristics that differ from one network to another,method characterized in that it includes: a location and selection stepfor a transmitter/receiver rendered capable by its geographic situationof communicating with at least two different communication networks, anda transmission step to a transmitter/receiver selected at the end of thelocation and identification step of characteristics specific tocommunication networks operational in the location where saidtransmitter/receiver was located. 2) Data transmission method as claimedin claim 1, characterized in that it also includes a configurationanalysis step for the transmitter/receiver selected at the end of thelocation and selection step and a step for evaluating a possiblecompatibility of said configuration with the characteristics specific tocommunication networks operational in the location where saidtransmitter/receiver was located. 3) Data transmission process asclaimed in one of claims 1 or 2, characterized in that it also includesa configuration adaptation step for the transmitter/receiver selected atthe end of the location and selection step, which adaptation step isintended to adapt said transmitter/receiver to at least onecommunication network operational in the location where saidtransmitter/receiver was located and distinct from a network with whichthe transmitter/receiver is already compatible. 4) Data transmissionprocess as claimed in one of claims 1 through 3, characterized in thatthe location and selection step is performed by triangulation. 5)Telecommunication system including at least one mobiletransmitter/receiver intended to be placed in communication with acommunication network selected from a multiplicity of such networks,said communication networks each having specific characteristics thatdiffer from one network to another, system characterized in that itincludes: means of location and selection of a transmitter/receiverrendered capable by its geographic situation of communicating with atleast two different communication networks, and transmission meansintended to send to a transmitter/receiver selected by the means oflocation and selection characteristics specific to communicationnetworks operational in the location where said transmitter/receiver waslocated. 6) Telecommunication system as claimed in claim 5,characterized in that it also includes configuration analysis means forthe transmitter/receiver selected at the end of the location andselection step and a step for evaluating a possible compatibility ofsaid configuration with the characteristics specific to communicationnetworks operational in the location where said transmitter/receiver waslocated. 7) Telecommunication system as claimed in one of claims 5 or 6,characterized in that it also includes means of configuration adaptationfor the transmitter/receiver selected at the end of the location andselection step, which adaptation means are intended to make saidtransmitter/receiver compatible with at least one communication networkoperational in the location where the transmitter was located anddistinct from a network with which the transmitter/receiver is alreadycompatible. 8) Telecommunication system as claimed in one of claims 5through 7, characterized in that the means of location and selectioninclude three base stations belonging to said networks for triangulatinga position of said transmitter/receiver. 9) Telecommunication system asclaimed in one of claims 5 through 7, characterized in that the means oflocation and selection include three satellites for triangulating aposition of said transmitter/receiver. 10) Radiotelephone capable ofperforming the functions of a mobile transmitter/receiver used in a datatransmission method as claimed in one of claims 1 through
 4. 11)Radiotelephone capable of performing the functions of a mobiletransmitter/receiver used in a telecommunication system as claimed inone of claims 5 through 9.